From 396daf31cb0dd4a964ccc784f9715e80381138cf Mon Sep 17 00:00:00 2001
From: Waylan Limberg <waylan@gmail.com>
Date: Thu, 24 May 2012 14:45:08 +0000
Subject: Fix #99. Account for empty header IDs when ensuring uniqueness.

---
 markdown/extensions/headerid.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/markdown/extensions/headerid.py b/markdown/extensions/headerid.py
index b0e37e2..c99c4bd 100644
--- a/markdown/extensions/headerid.py
+++ b/markdown/extensions/headerid.py
@@ -97,7 +97,7 @@ def slugify(value, separator):
 
 def unique(id, ids):
     """ Ensure id is unique in set of ids. Append '_1', '_2'... if not """
-    while id in ids:
+    while id in ids or not id:
         m = IDCOUNT_RE.match(id)
         if m:
             id = '%s_%d'% (m.group(1), int(m.group(2))+1)
-- 
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